Gas-operated firearm



Patented Jan. 9, 1940 :umrsi s'ra'rs GAS-OPERATED FIREARM Application August 4, 1937, Serial No. 157,234 In Hungary April 28, 1937 2 Claims.

Gun powder gases contain a considerable amount of solid mattersuch as soot, sediment and the like. Thus gas-operated machine guns are apt:to be unreliable when using such gun powder,

5 because the gas deposits in a short time such a large quantity of solid matter'on the wall of the gas cylinder, that the piston becomes jammed in the gas cylinder and the firearm is consequently prevented from operating.

The object of the present invention is the provision of a special construction of the gas cylinder, gas cylinder closure and gas piston in which construction, in the event of powder gases containing a large quantity of solid matter being used-as is occasioned by certain special climatic conditionsno harmful deposition can occur in the firearm between the gas piston and the gas cylinder.

According to the present invention, the vent of the gas passage extends with its muzzle in known manner into a cavity of the gas piston, and an annular dead space or pocket is provided at the bottom of the cavity in said gas piston where the flow direction of the gas is reversed. The dead pocket has a volume of a considerably greater capacity than is necessary for an unhindered flow of the powder gases. Thus, in said dead pocket, the flow is practically zero, so that the gases can deposit therein solid impurities thrown out by centrifugal force.

A second place for the deposition of solid impurities of the powder gases may be obtained by making the portion or" the gas cylinder adjacent the cylinder closure wider than the rest of the cylinder and providing a second annular dead space or pocket along the line of contact between the surface of the cylinder closure and the gas cylinder where a second reversal of the gas flow direction takes place.

Owing to the changes of direction the powder gases not only deposit part of their soot content in the pockets but also move the gas piston much more by their kinetic energy so that a gas-tight fit of the piston and cylinder is not so critical; 3 it is thus possible to leave a greater clearance between the gas cylinder and the gas piston. Owing to the second change of the direction, the powder gases deposit soot or sediment in the outer space once more at a part where it does not prejudice the operation of the firearm. The powder gases, which are thus very much cleaner, pass on to the part where the gas piston is fitted in the gas cylinder. Here, for the reasons already given, the clearance may be greater than has venticn as applied to a machine :gunisiillustrated in the accompanying drawing which shows the gas passage as well as the gas piston, gas cylinder and gas cylinder closure which co-operate to form the said gas operated mechanism.

The powder gas flows in the direction of the arrow 6 from a gun barrel G through a gas passage 3 formed in the gas cylinder l and in the gas cylinder closure 2 against the head of the gas piston 4 which is connected by a screwed joint to a piston rod 5.

The hollow head of the gas piston 4 has the form of a cylindrical body with a projecting central point I and an'annular pocket 8. The gas flows in the direction of the arrow 9 into the head of the piston 4, fills the pocket 8 under the action of the guide surface It and then flows back over and past the closure 2 in the direction of the arrow H between the closure 2 and the cylinder I. At this part of the gas passage the closure 2 is so shaped that an annular pocket is formed between it and the adjacent portion of the cylinder I. The gas flowing in the direction of the arrow H and guided by the guide surface l2 fills the annular pocket I3 after which its direction of flow is reversed and it passes rearwardly through the clearance between the cylinder i and the head of the gas piston 4.

Due to the double reversal of its direction of flow the gas. is freed of its solid matter in the pocketsB, l3. .These pockets however do not interfere with the continuous flow of the gas which reaches the clearance between the cylin der I and piston head 4 practically free'of impurities.

The individual parts of the firearm may be varied as regards their construction and operation without necessarily exceeding the limits of the present invention. Thus the form of the piston head 4 is not limited to that shown in the example described above; the piston may for instance have more than one annular pocket. Similarly the path of the gases may differ from that described: thus areversal of direction of the powder gases might for example take place in the cylinder closure 2. It is essential only that the path of the gas, before it reaches the clearance between the walls of the gas piston and of the gas cylinder, should have one or more places, provided with pockets or of enlarged cross section, where it changes direction and where the gas is freed of its solid constituents and passes on undisturbed.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:-

1. An automatic firearm, comprising a fixed barrel, a gas cylinder associated with said barrel and having a forward portion of greater width, than the rest of the cylinder, a stopper sealing the front end of said cylinder and being'formed with a passage for conducting gases from said barrel to said cylinder, said stopper including a rearwardly projecting tapered muzzle portion, and a gas piston slidable in said cylinder for operating the moving parts of the firearms, said piston being provided at its forward end with a substantially cylindrical cavity into which the rear end of said muzzle portion projects when the piston is in its forward position, whereby the space along the circular corner at the bottom of said cavity, where the flow direction of the gas is reversed for the first time, forms a first annular dead pocket, and the space between the cylinder wall and the muzzle portion along the base of the latter where the second reversal of the gas flow occurs, constitutes a second annular dead pocket.

2. An automatic firearm, comprising a fixed barrel, a gas cylinder'associated with said barrel, a stopper sealing the front end of said cylinder and being formed with a passage for conducting gases from said barrel to said cylinder, said stopper including a rearwardly projecting tapered muzzle portion, and a gas piston slidable in said cylinder for operating the moving parts of the firearm, said piston being provided at its forward end with a substantially cylindrical cavity and having a substantially conical guide surface with a central forwardly projecting point forming the bottom of said cavity into which latter the rear FERENC GEBAUER. 

